Many cell phones are designed in a way that conserves space, making it easier for a user to carry. Some of the cell phones are designed as two rotatably connected housings that rotate or pivot open and then closed. These cell phones are known as “clamshell phones” or “rotator phones” depending on the orientation of the hinge to the housing halves. A clamshell phone typically includes a base portion, a rotatable portion, and a hinge to pivotally connect the base portion and the rotatable portion. When not in use, the rotatable portion usually lays flush against the base portion. In the event that the user desires to utilize the phone to make a phone call, send a text message, or view information stored in a memory of the phone, the user can open the phone by rotating the rotatable portion open. When a user opens the phone, the rotatable portion angularly rotates or pivots with respect to the hinge.
Clamshell phones often include a display and other elements, such as a camera lens, affixed to the rotatable portion. The base portion typically includes a processor that controls many elements of the clamshell phone, including elements located in the base portion as well as elements located in the rotatable portion. Due to the presence of the processor in the base portion and the need for various electronic components of the base portion needing to communicate with various electronic components in the rotatable portion, a communication path is required between the base portion and the rotatable portion.
There have been proposals of clamshell phones in the art that utilize fiber optic cables to transmit light signals from the base portion to the rotatable portion. The use of fiber optic cables, however, can be very expensive and the fiber optic cables can wear down and lose fidelity after substantial repeated opening and closing of the respective rotatable phones and portable notebook computers. Such fiber optical cables also cannot be molded into various shapes for ease of use within such rotatable phones and portable notebook computers.
Traditionally, copper wiring has been used as the communication path. When copper wiring is used, there is often a need for 50-60 copper wire lines between the rotatable portion and the base portion. These copper wire lines have been placed in a multi-layer (e.g., four or five layers are often used) flexible circuit extending between the base portion and the rotatable portion. The layers may be formed of a flexible plastic material in which the copper lines are mounted. The use of copper wiring is, however, problematic. For example, the use of the copper wiring can result in electromagnetic (“EM”) radiation that affects the transmission across adjacent copper wires. The EM radiation results in noise that can adversely affect data transmission.
Some systems have reduced the number of lines by serializing the lines, resulting in fewer but higher speed lines. When the lines are serialized, multiple lines of data can be transmitted across a single line at different times. For example, the data for the first line may be transmitted, followed by the data for the second line, and then data for the third line, across a single copper line. A serialization embodiment is also subject to the same EM radiation problems that occur without serialization and could interfere more with cellular bands because the higher speed serialized signal is closer to the cellular band.
Another problem with using flexible circuits is their inherent unreliability. Specifically, the flexible circuits require use of many connectors that can lose their fidelity over time and use. Furthermore, flex copper lines can break down over extended use following many hundreds of rotational open/close bending. The physical connections required in current systems in the art are therefore problematic
Optical communication following the process of serialization provides a viable solution to such problems. Serialization minimizes the number of data lines (e.g., possibly down to one data line) at the expense of higher speed. This makes the use of optical communication very practical due to the limited data lines (one transceiver is needed). Furthermore, low cost optical diodes (e.g., Vertical Cavity Surface Emitting Lasers (“VCSELs”)) are readily available today and very capable of high speeds in the GHz range.
An additional problem with current clamshell phones is the requirement of circuitry to detect when the phone is in the open position or whether it is closed so that the phone knows whether to power the display or other circuitry in the rotatable portion and/or in the base portion.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention. Also, common and well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.